Per- and polyfluoroalkyl substances (PFAS) are commonly used in proton exchange membrane fuel cells due to their high stability and resistance. These ionomers act as binding agents and their hydrophobic effect helps to remove excess water from the gas diffusion layer. Their proton conductivity and hydrophobicity, gained by incorporation of functional side chains, are essential features for their application as membranes.. However, the harsh conditions in fuel cells can lead to degradation of PFAS compounds, which are released into the environment. Due to their persistence, there are growing concerns about the enrichment of PFAS in groundwater and soil. As these substances accumulate in the environment, they are incorporated by living organisms through drinking water and plants. Some of these substances are associated with causing health disorders, such as cancer, brain and liver damage, and negative impacts on embryo development. This review highlights the sources of PFAS during fuel cell production, operation and recycling and currently available alternatives used in proton exchange membrane fuel cells. The degradation of fuel cells during operation has the potential to result in the emission of PFAS. Membrane degradation mechanisms have been investigated and results can serve as a foundation to reduce PFAS emissions by identifying critical operating conditions.

Remediating soils contaminated by per- and polyfluoroalkyl substances (PFAS) is a challenging task due to the unique properties of these compounds, such as variable solubility and resistance to degradation. In-situ soil flushing with solvents has been considered as a remediation technique for PFAS-contaminated soils. The use of non-Newtonian fluids, displaying variable viscosity depending on the applied shear rate, can offer certain advantages in improving the efficiency of the process, particularly in heterogeneous porous media. In this work, the efficacy of ethanol/xanthan mixture (XE) in the recovery of a mixture of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), and perfluorobutane sulfonate (PFBS) from soil has been tested at lab-scale. XE's non-Newtonian behavior was examined through rheological measurements, confirming that ethanol did not affect xanthan gum's (XG) shear-thinning behavior. The recovery of PFAS in batch-desorption exceeded 95 % in ethanol, and 99 % in XE, except for PFBS which reached 94 %. 1D-column experiments revealed overshoots in PFAS breakthrough curves during ethanol and XE injection, due to oversolubilization. XE, (XG 0.05 % w/w) could recover 99 % PFOA, 98 % PFBS, 97 % PFHxS, and 92 % PFOS. Numerical modeling successfully reproduces breakthrough curves for PFOA, PFHxS, and PFBS with the convection-dispersion-sorption equation and Langmuir sorption isotherm.

This study aims to explore the effects of arbuscular mycorrhizal fungi (AMF) on the growth of Iris pseudacorus L. and treatment efficacy in constructed wetlands (CWs) subjected to stress from per-and poly-fluoroalkyl substances (PFASs). The findings reveal that PFASs exposure induces oxidative damage and inhibits the growth of I . pseudacorus. However, AMF symbiosis enhances plant tolerance to PFAS stress by modulating oxidative responses. AMF treatment not only promoted plant growth but also improved photosynthetic efficiency under PFAS exposure. Compared to non-AMF treatment, those with AMF treatment exhibited significantly increased levels of peroxidases and antioxidant enzymes, including peroxidase and superoxide dismutase, along with a notable reduction in lipid peroxidation. Additionally, AM symbiosis markedly enhanced the efficacy of CWs in the remediation of wastewater under PFASs-induced stress, with removal efficiencies for COD, TP, TN, and NH4+- N increasing by 19-34%, 67-180%, 106-137%, and 25-95%, respectively, compared to the AMF- treatments. In addition, the metabolic pathways of PFASs appeared to be influenced by their carbon chain length, with long- chain PFASs like perfluorooctanoic acid (PFOA) and perfluoro anionic acid (PFNA) exhibiting more complex pathways compared to short-chain PFASs such as perfluoro acetic acid (PFPeA), and perfluoro hexanoic acid (PFHpA). These results suggest that AMF-plant symbiosis can enhance plant resilience against PFAS-induced stress and improve the pollutant removal efficiency of CWs. This study highlights the significant potential of AMF in enhancing environmental remediation strategies, providing new insights for the more effective management of PFAS-contaminated ecosystems.

The efficacy of RemBind (R) 300 to immobilize per- and polyfluoroalkyl substances (PFAS) in aqueous film forming foam (AFFF)-impacted soil (& sum;(28) PFAS 1280-8130 ng g(-1); n = 8) was assessed using leachability (ASLP) and bioaccumulation (Eisenia fetida) endpoints as the measure of efficacy. In unamended soil, & sum;(28) PFAS leachability ranged from 26.0 to 235 mu g l(-1), however, following the addition of 5% w/w RemBind (R) 300, & sum;(28) PFAS leachability was reduced by > 99%. Following exposure of E. fetida to unamended soil, & sum;(28) PFAS bioaccumulation ranged from 18,660-241,910 ng g(-1) DW with PFOS accumulating to the greatest extent (15,150-212,120 ng g(-1) DW). Biota soil accumulation factors (BSAF) were significantly (p < 0.05) higher for perfluoroalkyl sulfonic acids (PFSA; 13.2-50.9) compared to perfluoroalkyl carboxylic acids (PFCA; 1.2-12.7) while for individual PFSA, mean BSAF increased for C-4 to C-6 compounds (PFBS: 42.6; PFPeS: 52.7; PFHxS: 62.4). In contrast, when E. fetida were exposed to soil amended with 5% w/w RemBind (R) 300, significantly lower PFAS bioaccumulation occurred (& sum;(28) PFAS: 339-3397 ng g(-1) DW) with PFOS accumulation 23-246 fold lower compared to unamended soil. These results highlight the potential of soil amendments for reducing PFAS mobility and bioavailability, offering an immobilization-based risk management approach for AFFF-impacted soil.

Soils contaminated with per- and poly- fluoroalkyl substances (PFAS) require immediate remediation to protect the surrounding environment and human health. A novel animated clay -polymer composite was developed by applying polyethyleneimine (PEI) solution onto a montmorillonite clay-chitosan polymer composite. The resulting product, PEI -modified montmorillonite chitosan beads (MMTCBs) were characterized as an adsorptive soil amendment for immobilizing PFAS contaminants. The MMTCBs exhibited good efficiency to adsorb the PFAS, showing adsorption capacities of 12.2, 16.7, 18.5, and 20.8 mg g -1 for PFBA, PFBS, PFOA, and PFOS, respectively, which were higher than those obtained by granular activated carbon (GAC) (i.e., an adsorbent used as a reference). Column leaching tests demonstrated that amending soil with 10% MMTCBs resulted in a substantial decrease in the leaching of PFOA, PFOS, PFBA, and PFBS by 90%, 100%, 64%, and 68%, respectively. These reductions were comparable to the values obtained for GAC-modified soil, particularly for long -chain PFAS. Incorporating MMTCBs into the soil not only preserved the structural integrity of the soil matrix but also enhanced its shear strength (kPa). Conversely, adding GAC to the soil resulted in a reduction of the soil ' s mechanical properties.

Cyclic C6O4 (cC(6)O(4), CAS number 1190931-27-1) is a perfluoralkyl ether PFAS used as a polymerization aid in the synthesis of fluoropolymers and produced in Italy since 2011 as substitute of PFOA. To date, available ecotoxicological information on cC(6)O(4) is related to regulatory requirements and limited to data on aquatic organisms, while the information on the effects for terrestrial organisms is completely lacking. This work reports the first ecotoxicological data of cC(6)O(4) on terrestrial invertebrates: short- and long-term toxicity of cC(6)O(4) on Eisenia foetida (Savigny, 1826), exposed to spiked soil under laboratory conditions, was investigated evaluating the earthworm survival and growth (observed after 7, 14 and 28 days of exposure), and reproduction (observed after an exposure period of 56 days). Furthermore, also bioaccumulation was investigated (28 days of exposure); overall results are discussed in comparison with literature data available for legacy PFAS. cC(6)O(4) did not cause significant mortality on earthworms, for any of the tested concentrations and exposure periods (NOEC: > 1390 mg/kg d.w.), while the reproduction (measured as juveniles production) appears to be a more sensitive endpoint (EC50: 10.4 mg/kg d.w., EC10: 0.8 mg/kg d.w.). The observed adverse effects occur at levels significantly higher than realistic soil concentrations and cC(6)O(4) appears to be less toxic than PFOA and PFOS. As for bioaccumulation, the results indicate a negligible bioaccumulation potential of cC(6)O(4), whose Biota-Soil Bioaccumulation Factors (BSAF) are significantly lower than all other considered PFAS.